Rectifier and inverter



Dec. 15, 1936. R. LUDWIG ET AL 2,064,020

RECTIFIER AND INVERTER Filed Jan. 6, 1953 INVENTORS.

' LeonffiLuan/z'y and I 81 J%/%2 gfP EPIC? ATTORNEY Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE RECTIFIER AND INVERTER Leon R. Ludwig,

Wilkinsburg,

and Joseph Vania Application January 6, 1933, Serial No. 650,413

5 Claims.

Our invention relates to starter circuits for vapor electric devices and particularly to circuits for controlling the ignition point of makealive devices in vapor electric apparatus.

In vapor-electric devices such as vectrions in which a make-alive electrode is controlled by the anode potential, it is found that substantially 40 or volts potential above the cathode must be applied to the anode before the make-alive -.wil1 become operative. When the make-alive is fed directly from the anode, the difference in potential necessary to produce the make-alive current causes the anode current to lag materially behind the anode voltage and consequently reduces the power factor of the rectifying device.

It is an object of our invention to provide means for introducing an auxiliary voltage into the make-alive circuit to eliminate the initial lag of anode current behind the anode voltage.

In many cases, it is desirable to control the output voltage of a vapor-electric device when such devices are controlled by make-alive electrodes. The output voltage may conveniently be controlled by controlling the ignition point of the make-alive circuit.

According to our invention, a suitable biasing potential may be introduced into the make-alive circuit so that the make alive current will be initiated at any desired point on the anodevoltage wave. Also, when vapor-electric devices are used for converting direct current to alternating current, it is necessary to start the arc only within quite definite portions of the alternating-voltage wave impressed on the anode. In the apparatus according to our invention, the auxiliary voltage may be displaced in phase relationship to the anode voltage any amount necessary to produce the desired ignition characvteristic.

Other objects and advantages will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which Figure 1 is a schematic view of a rectifier system embodying our invention.

Fig, 2 is a similar view showing a separate transformer for providing the auxiliary voltage.

Fig. 3 is a schematic illustration of a polyphase rectifying transformer showing the auxiliary voltage source associated with the phase other than that to which it is connected.

Fig. 4 shows the use of an independent generator for producing a biasing potential.

Fig. 5 shows a direct-current bias, and

Fig. 6 shows an auxiliary voltage source controlled by the anode potential.

In apparatus according to our invention, rectifiers I consisting of a vaporizable cathode 2 and a closely spaced anode 3 is provided with a 5 suitable make-alive device 5 such as that described in our copending application, Serial No. 626,866, filed July 30, 1932. A suitable transformer 6 is provided for supplying alternating current to the anodes 3, the cathodes 2 being 10 connected to a suitable direct current bus I. While, in normal operation, our rectifying system will operate polyphase, we have, for purposes of convenience, illustrated only one phase as connected to the rectifier.

In the simplest form of our invention according to Fig. l, a suitable auxiliary winding I0 is placed in the transformer 6 and associated with the phase normally connected to the anode 3. An auxiliary rectifying device I2 is connected 20 in the lead I3 between the auxiliary winding I0 and the make-alive electrode 5. As the voltage increases in a positive direction in the phase connected to the anode 3, the anode voltage increases to a point equal to or above the cathode 25 potential. At the same time, the auxiliary voltage also increases in a positive direction. This auxiliary voltage may be regulated by varying this point of connecting lead I3 so that the necessary make-alive voltage, which consists of 30 the normal anode voltage plus the voltage of the auxiliary winding I0, is suflicient to activate the make-alive 5 and initiate a cathode spot at any desired period on the voltage characteristic. A suitable switch I5 may be inserted 35 in the make-alive circuit l3 for controlling the rectifier without interrupting the load current in the rectifying device.

In the modification according to Fig. 2, the auxiliary voltage is introduced by a separate 40 transformer 26. This separate transformer may be connected to the main power source through a suitable phase shifting device 2I so that the make-alive voltage may be shifted in relation to the anode'potential.

In the modification according to Fig. 3, the auxiliary winding 25 for producing the auxiliary make-alive potential is associated with a phase other than that to which the anode is connected. By properly proportioning the auxiliary winding 50 25, the ignition point of the make-alive circuit can be established wherever desired. If the auxiliary winding is associated with a phase in advance of that to which the anode is connected, the potential in the make-alive circuit will decay ahead of the potential in the anode circuit so that the make-alive circuit will be extinguished before the main rectifying arc is extinguished.

The quick suppression of the make-alive current not only eliminates the loss of energy in the make-alive circuit but if the keep-alive were allowed to operate after the main rectifying arc was extinguished the ionization produced by the make-alive might cause back-fire in the rectifier.

In the modification according to Fig. 4, the auxiliary voltage is introduced into the makealive circuit by a suitable auxiliary generator 21. The ignition point of the make-alive may be controlled by changing the phase relationship or the frequency in the auxiliary generator.

In the modification according to Fig. 5, the biasing potential for the make-alive circuit is obtained from an auxiliary battery 29 connected in series between the anode potential and the make-alive electrode 5. In order to interrupt the make-alive current before the extinguishment of the main rectifying arc, a suitable commutating device 36 may be introduced in the make-alive circuit. We prefer to use both an auxiliary rectifier and the synchronous commutator, however for some applications the auxiliary rectifier may be omitted.

In the modification according to Fig. 6, the make-alive current is provided from an auxiliary power source such as a direct current generator 32. A current-limiting resistor 33 is placed in series with the generator 32 and the entire generator and resistor shunted by a suitable capacitor 34. A grid-controlled auxiliary rectifier 36 is placed between the generator 32 and the make-alive electrode 5, the grid 3? of the auxiliary rectifier being controlled by the potential applied to the anode S. A suitable biasing potential 38 may be introduced between the anode 3 and the control grid 3'! of the auxiliary rectifier for controlling the ignition point with regard to the potential of the transformer 6. When the grid 31 of the auxiliary rectifier is positive with respect to the make-alive electrode 5 the auxiliary rectifier 36 will permit current flow in the make-alive circuit. The series resistor 33 in the make-alive circuit is so chosen that the current fiow from the generator 32 will be insuificient to provide the necessary makealive current. However, the generator will charge up the capacitor 34 to a voltage equal to the generator voltage and when the auxiliary rectifier 36 breaks down, the capacitor 34 will discharge in parallel with the auxiliary generator 32 to produce suificient current to activate the make-alive device 5 and then as the capacitor current is expended, the make-alive device will become inactive and allow the make-alive to be extinguished prior to the extinguishing of the main rectifying arc in the rectifier.

While we have shown and described specific embodiments of our invention, it is apparent that changes and modifications can be made therein without departing from the spirit and scope of our invention. We desire, therefore, that only such limitations shall be imposed as are necessitated by the prior art or as are incorporated in the accompanying claims.

We claim as our invention:

1. A conversion system comprising a mercury arc device, an alternating current circuit, a transformer connected to said circuit and to said rectifier, a make-alive electrode in said rectifier, a circuit connecting said make-alive to said transformer so that said make-alive derives a voltage from said transformer, an auxiliary source of alternating current in said make alive circuit and polarity responsive means for controlling the fiow of current in said make alive circuit and means for shifting the phase relation of the auxiliary voltage with respect to the transformer voltage.

2. An ignition system for a vapor electric device having an anode and a cathode, comprising an alternating current circuit, a transformer in said circuit connected to said device, a direct current circuit connected to said device, a makealive electrode in said device, said make-alive electrode being connected to said transformer so as to receive potential therefrom an auxiliary current source connected to said make-alive electrode and to said transformer and a rectifier connected between said make-alive and said transformer for applying voltage to said makealive in response to the potential of the alternating circuit and means for shifting the phase relation of the auxiliary voltage.

3. An ignition system for a vapor electric converter comprising a vapor electric device having an anode and a cathode, an auxiliary makealive electrode in said device, an auxiliary voltage source adopted for connection to said makealive and means responsive to the voltage applied to the anode for initiating the ignition period of the make alive, and means for terminating the current in the make alive prior to the termination of the current between the anode and the cathode.

4. An ignition system, for a vapor-electric device, having an anode and a cathode comprising a make-alive electrode in said device, a main transformer winding having one terminal connected to said anode, a direct current bus connected to said cathode, an auxiliary winding in said transformer connected between said main winding and said make-alive electrode and means in the make-alive circuit responsive to the polarity of the transformer for permitting current flow to said make alive.

5. An ignition system, for a vapor-electric device, having an anode and a cathode comprising a make-alive electrode in said device, a main transformer winding having one terminal connected to said anode, a direct current bus connected to said cathode, an auxiliary winding in said transformer connected between said main winding and said make-alive electrode and means in the make-alive circuit responsive to the polarity of the transformer for permitting current flow to said make alive, said auxiliary winding being associated with a phase different from that to which it is connected.

LEON R. LUDWIG. JOSEPH SLEPIAN. 

